Metal bonded drilling and boring tool

Abstract

A metal bonded drilling and boring tool which can prevent the separation of abrasive grains during drilling and boring to maintain a stable working performance for a long period of time without the need for tool exchange. The tool includes a rod-shaped body having a substantially semispherical front end portion and numerous abrasive grains bonded to an outer circumferential surface of the rod-shaped body at the front end portion and at a portion having a given length from the front end portion by a bond member formed primarily of copper alloy. The bond member contains a material selected from the group consisting of Ti, Al, and a mixture thereof. The copper alloy is selected from the group consisting of bronze containing 10 to 33 wt % of Sn, brass containing 5 to 20 wt % of Zn, and aluminum bronze containing 5 to 20 wt % of Al.

1. A metal bonded drilling and boring tool comprising:
 a rod-shaped body having a substantially semispherical front end portion at a center thereof and a first diameter said rod-shaped body being solid in cross-section; 
 an enlarged mounting portion having a second diameter larger than said first diameter, said enlarged mounting portion having a mounting hole with an internal screw thread; 
 a connecting portion connecting said rod-shaped body and said enlarged mounting portion; and 
 numerous abrasive grains brazed by a brazing member to an outer circumferential surface of said rod-shaped body at said front end portion and extending a given length from said front end portion to include a part of said connecting portion, 
 wherein said rod-shaped body has an arcuate depression formed on said front end portion at the center and in the vicinity thereof, wherein said arcuate depression defines an arc extending into the rod-shaped body in an axial direction with endpoints along a circumferential interface between said depression and said front end portion surrounding said depression. 
 
   
   
     2. A metal bonded drilling and boring tool according to  claim 1 , wherein said connecting portion has a concave surface continuing to the outer circumferential surface of said rod-shaped body. 
   
   
     3. A metal bonded drilling and boring tool according to  claim 1 , wherein said connecting portion has a frustoconical shape. 
   
   
     4. A metal bonded drilling and boring tool according to  claim 1 , further comprising an elastic member bonded to a bottom surface of said mounting hole. 
   
   
     5. A metal bonded drilling and boring tool comprising:
 a rod-shaped body having a substantially semispherical front end portion and a first diameter; 
 an enlarged mounting portion having a second diameter larger than said first diameter, said enlarged mounting portion having a mounting hole with an internal screw thread; 
 a connecting portion connecting said rod-shaped body and said enlarged mounting portion; and 
 numerous abrasive grains brazed to an outer circumferential surface of said rod-shaped body at said front end portion and at a portion having a given length from said front end portion by a brazing member; 
 said brazing member comprises a bond member formed primarily of copper alloy; 
 said bond member containing a material selected from the group consisting of Ti, Al, and a mixture thereof; 
 an average abrasive grain projection height being set to 30% or more of an average abrasive grain diameter, where said abrasive grain projection height is defined as a distance between the surface of a deepest portion of said bond member present between any two adjacent ones of said abrasive grains and the top of each of said two adjacent abrasive grains; and 
 an average abrasive grain spacing being set to 200% or more of said average abrasive grain diameter, where said abrasive grain spacing is defined as a distance between the tops of said two adjacent abrasive grains. 
 
   
   
     6. A metal bonded drilling and boring tool according to  claim 5 , wherein said rod-shaped body has at least one escape portion formed on said portion having said given length. 
   
   
     7. A metal bonded drilling and boring tool according to  claim 5 , wherein said rod-shaped body has at least one groove formed on said front end portion. 
   
   
     8. A metal bonded drilling and boring tool comprising:
 a rod-shaped body having a substantially semispherical front end portion at a center thereof, and a first diameter said rod-shaped body being solid in cross-section; 
 an enlarged mounting portion having a second diameter larger than said first diameter; 
 a connecting portion connecting said rod-shaped body and said enlarged mounting portion; and 
 numerous abrasive grains brazed by a brazing member to an outer circumferential surface of said rod-shaped body at said front end portion and extending a given length from said front end portion to include a part of said connecting portion, 
 wherein said rod-shaped body has an arcuate depression formed on said front end portion at the center and in the vicinity thereof, wherein said arcuate depression defines an arc extending into the rod-shaped body in an axial direction with endpoints along a circumferential interface between said depression and said front end portion surrounding said depression. 
 
   
   
     9. A metal bonded drilling and boring tool according to  claim 8 , wherein said connecting portion has a concave surface continuing to the outer circumferential surface of said rod-shaped body. 
   
   
     10. A metal bonded drilling and boring tool according to  claim 8 , wherein said connecting portion has a frustoconical shape. 
   
   
     11. A metal bonded drilling and boring tool according to  claim 8 , wherein the depression seatably holds the abrasive grains. 
   
   
     12. A metal bonded drilling and boring tool comprising:
 a rod-shaped body having a substantially semispherical front end portion and a first diameter; 
 an enlarged mounting portion having a second diameter larger than said first diameter; 
 a connecting portion connecting said rod-shaped body and said enlarged mounting portion; and 
 numerous abrasive grains brazed to an outer circumferential surface of said rod-shaped body at said front end portion and at a portion having a given length from said front end portion by a brazing member; 
 said brazing member comprises a bond member formed primarily of copper alloy; 
 said bond member containing a material selected from the group consisting of Ti, Al, and a mixture thereof; 
 an average abrasive grain projection height being set to 30% or more of an average abrasive grain diameter, where said abrasive grain projection height is defined as a distance between the surface of a deepest portion of said bond member present between any two adjacent ones of said abrasive grains and the top of each of said two adjacent abrasive grains; and 
 an average abrasive grain spacing being set to 200% or more of said average abrasive grain diameter, where said abrasive grain spacing is defined as a distance between the tops of said two adjacent abrasive grains. 
 
   
   
     13. A metal bonded drilling and boring tool according to  claim 12 , wherein said rod-shaped body has at least one escape portion formed on said portion having said given length. 
   
   
     14. A metal bonded drilling and boring tool according to  claim 12 , wherein said rod-shaped body has at least one groove formed on said front end portion. 
   
   
     15. A metal bonded drilling and boring tool according to  claim 1 , wherein the depression seatably holds the abrasive grains.